1. Field
The disclosure relates generally to a computer implemented method, hardware enabled computer instructions, and a data processing system. More specifically, this disclosure relates to a computer implemented method, hardware enabled computer instructions, and a data processing system for a hardware controlled, software assist lookaside table search technique.
2. Description of the Related Art
Increasingly large symmetric multi-processor data processing systems are not being used as single large data processing systems. Instead, these types of data processing systems are being partitioned and used as smaller systems. These systems are also referred to as logical partitioned (LPAR) data processing systems. A logical partitioned functionality within a data processing system allows multiple copies of a single operating system or multiple heterogeneous operating systems to be simultaneously run on a single data processing system platform. A partition, within which an operating system image runs, is assigned a non-overlapping subset of the platforms resources. These platform allocable resources include one or more architecturally distinct processors and their interrupt management area, regions of system memory, and input/output (I/O) adapter bus slots. The partition's resources are represented by the platform's firmware to the operating system image.
Each distinct operating system or image of an operating system running within a platform is protected from each other, such that software errors on one logical partition cannot affect the correct operation of any of the other partitions. This protection is provided by allocating a disjointed set of platform resources to be directly managed by each operating system image and by providing mechanisms for ensuring that the various images cannot control any resources that have not been allocated to that image. Furthermore, software errors in the control of an operating system's allocated resources are prevented from affecting the resources of any other image. Thus, each image of the operating system, or each different operating system, directly controls a distinct set of allocable resources within the platform.
With respect to hardware resources in a logical partitioned data processing system, these resources are shared dis-jointly among various partitions. These resources may include, for example, input/output (I/O) adapters, memory DIMMs, non-volatile random access memory (NVRAM), and hard disk drives. Each partition within a logical partitioned data processing system may be booted and shut down over and over without having to power-cycle the entire data processing system.
In software managed memory management systems, translation lookaside buffer look-up/search operations become problematic and slow process when translation lookaside buffer size becomes large. In embedded central processing unit core design, which focuses on power and size, software managed approach is more prevalent rather than hardware managed to reduce logic space.
A small translation lookaside buffer size can be simply implemented in a fully associative structure. However, as translation lookaside buffer size becomes larger, a set-associative structure becomes more a desirable implementation. The set-associative structure provides for faster performance within the translation lookaside buffer, due to the simultaneous comparisons of many entries that are required in full associative implementations.
However, because of the table size and many page size variations within a large translation lookaside buffer, even in a set-associative structure, look-up and search operations of the translation lookaside buffer become very process intensive. Operation of the large translation lookaside buffer often gets worse when the large translation lookaside buffer table index is hashed to reduce hot spots as seen in many applications.